Convective Weather Forecasting: "Forecaster over the Loop" Programs
Example of the ANC web display made available to meteorologists at the Dallas/Fort Worth CWSU. The blue regions indicate areas where new storm initiation is forecast and the yellow/reds indicate the one hour growth/decay forecasts of existing storms.
The research and development efforts of RAL's Convective Weather Group are aimed at improving short-term (0 – 6 hour) thunderstorm forecasting and bridging the gap in skill between observation-driven expert systems and numerical weather prediction. One of the most important tools used by this group is the AutoNowcaster (ANC), an automated system developed at RAL that provides short-term forecasts of atmospheric convection based on extrapolation of current radar echoes, model output and mesoscale fields in the path of convection. For the past several years, work has focused on the value human forecasters could potentially add to convective weather forecasts generated by the ANC. This effort, which has come to be known as "Forecaster over the Loop", was launched in FY04 in Dallas Fort Worth (DFW) with National Weather Service support. A smaller program funded by Weather Services International (WSI) was also conducted in FY06.
FY06 Accomplishments:
A regional installation of the ANC system has been running in the DFW Weather Forecast Office (WFO) area for several years. The most important update made to the system this past year was the inclusion of improved tools that allow the local forecasters to interact with the real-time system in an efficient manner to improve overall system performance. This upgrade involved working with the local forecasters to identify several convective regimes that may be selected by a user based on the type of weather anticipated in the near future. The forecast logic for each of these regimes was fine-tuned utilizing the specific predictor fields that are pertinent to an expected type of convective activity. During this summer's operations, significant improvements over extrapolation were oftentimes realized during the initiation phase of convective events. Moreover, feedback from the DFW forecasters has been very positive. Another new aspect of the installation running at the DFW WFO is the inclusion of a web page display that is also being viewed by the forecasters at the Center Weather Service Unit (CWSU) to assist them in their forecasting duties to support air traffic management personnel. An example of this web display is provided in the figure below. A similar demonstration effort was conducted as part of an FAA-supported Illinois Indiana Forecast Demonstration installation of the ANC. Over a three-month period WSI forecasters interacted with the system each day during the hours when convective initiation is most likely to occur in that region. Roughly 25 convective initiation events occurred during the three-month demonstration.
FY07 Plans:
Periods of time during which storms initiated will be cataloged and rerun to produce a second set of forecasts without forecaster input. Comparison of the two sets of forecasts will be made to assess how the forecaster impacted the final forecasts both qualitatively and quantitatively and as a function of the chosen regime.